Read the link to ML, agree totally different speaker design, I would however not want people to think the Sound Labs are all huge speakers, yes, they do make some that are nearly 9ft tall, however, mine measure a bit under six feet and are around 30" wide and fit well in my present room.
The fellow who said he has "heard" them (SL) and found them cool, was rebutted by the others, I would agree, the speaker is neutral with extreme clarity but the treble is very sweet sounding, by adding or removing bias from the panel you can change the sound, however, what is really happening especially with sand amps is as you remove bias you lose sensitivity, with the high impedance in the bass the amplifier cannot keep up and the sound distorts with the very low impendance for the treble again the amp struggles. The best sand amps for these speakers incorporate many capacitors for energy storage in their design. Tube amps do a bit better with the voltage swings the tube make possible, but as I said earlier selection of the amplifier and other upstream gear is key. The BAT Pre-amp I use does have nice synergy with the Wolcotts along with the Musical Fidelity KW SACD and a heavily modded Rega P-25 TT.
EL-34 tubes are readily available, somewhere around 25 each, average around five years lifetime depending on use, so retubing is not really all that expensive to me, there is one of the driver side tubes the 6gw8 becoming a bit rare, each amp takes two, right now they are running 75 each but they last up to 10 years, the other two driver tubes are common 12ax7, available all over the net, the circuit design does not require matched tubes additionally tube rolling is not recommended as the design does not allow tube coloration of the signal.
Here are some more shots of the speakers.